Rotary switch



v Dec. 19, 1967 W, HEATH 3,359,392

ROTARY SWITCH Original Filed May 26, 1965 x z2 a 2 w/ 72 13a 2 X2 "'90 9 2 I -b INvEN-roQ AT-TQEwEY United States Patent 3,359,392 ROTARY SWITCH Clarence Willans Heath, Bleasby, England, assignor to United-Carr Incorporated, Boston, Mass, a corporation of Delaware Continuation of application Ser. No. 458,931, May 26, 1965. This application Apr. 27, 1967, Ser. No. 634,391 Claims priority, application Great Britain, May 28, 1964, 22,122/ 64 1 Claim. (Cl. 200-153) ABSTRACT OF THE DISCLOSURE This invention relates to a movable contact for use in a rotary switch, having a split arm which has a free terminal end with a contact element or pip, and has an arced flexible tongue with a free terminal end which is engageable with an actuating element for applying force against the tongue. The tongue being constructed to absorb excessive pressures of the actuating element, isolating these excessive pressures from the contact portion of the arm.

This is a continuation of application 458,931 originally filed May 26, 1965, and now abandoned.

This invention relates to a rotary switch comprising a movable contact adapted to be moved relatively to a fixed contact to open or close the switch circuit by a rotor.

When such a movable contact is actuated by the rotor into engagement with the fixed contact, it is important that suflicient pressure is exerted by the rotor to efiect a good electrical engagement between the contacts, but if the pressure is excessive, there is a tendency for the movable contact to be overstressed causing damage or fracture of the contact or producing a set which will impair the efiicient operation of the switch.

It is an object of the present invention to provide an arrangement which overcomes this drawback.

According to the present invention, the pressure of the rotor is transmitted to the movable contact through resilient means on the movable contact so that any pressure in excess of that necessary to eflect the engagement of the contacts is absorbed by the resilient means.

The movable contact may comprise a resilient strip of metal having a pip contact provided on its free end for co-operative engagement with a fixed contact in the switch, the other end being secured to part of the switch so as to be capable of a flexing or hinge-like movement towards and away from the fixed contact. The resilient means may comprise a resilient tongue bent outwardly of the plane of the strip at a position spaced from the free end so as to be engageaible by the rotor.

The rotor may be of cam-like form having a lobe engageable with the resilient means to transmit pressure to the movable contact to urge it into engagement with the fixed contact, the movable contact automatically flexing out of engagement when the rotor is moved into a position wherein the lobe no longer engages the resilient means.

The switch may comprise a plurality of modules, each of disc-like form, the modules being co-axially mounted on a common shaft and each module being adapted to actuate a movable contact provided with said resilient means.

To enable the invention to be fully understood, it will now be described, by Way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a perspective view illustrating one form of movable contact;

FIGURE 2 is a diagrammatic illustration of the contact mounted in a switch showing a movable contact out of engagement with a fixed contact;

FIGURE 3 is a view similar to FIGURE 2, but showing the movable contact displaced by the rotor into engagement with the fixed contact;

FIGURE 4 is a side view of a switch embodying the contacts;

FIGURE 5 is a plan view of the switch illustrated in FIGURE 4; and

FIGURE 6 is a sectional view on the line A-A of FIGURE 4.

As shown in FIGURES 1 to 3 of the drawings, the movable contact is formed from a strip of resilient metal comprising an arm 1 having a contact pip 2 at its free end. Adjacent the opposite end the strip is reversely bent to provide a bight portion 3 and a base portion 4 adapted to rest on part of the switch body and a lug 5 for attachment to a lead wire. As shown, a portion of the arm 1 intermediate the ends is cut and bent to form a resilient tongue 6 extending out of the plane of the body. This tongue extends into the path of a cam-shaped rotor 7 which has a lobe 8 so that in effect the resilient tongue forms a follower for the cam.

The arm 1 of the strip is hingeable about the bight 3 so that when not engaged and flexed by the rotor, it will automatically revert to its normal at rest position indicated in FIGURE 2. When the rotor is rotated into the position indicated in FIGURE 3, the lobe 8 engages the resilient tongue 6 and transmits pressure to flex the arm 1 into engagement with the fixed contact 9 to close the circuit through the contacts. If the resilient tongue were not provided, it would be necessary for the pressure exerted by the lobe 8 to be very accurately determined to ensure that sufficient pressure was exerted to eflect the engagement of the contacts without overstressing the contact arm 1. With the applicants arrangement, however, any excess pressure exerted by the lobe is absorbed by the resilient tongue by flexing into the position indicated in FIGURE 3 so that the arm 1 of the strip will not be overstressed. It will be understood that by varying the dimensions of the tongue and the extent it projects from the arm 1, the engagement pressure of the contacts 2 and 9 may be accurately controlled.

The application of the invention to a switch comprising a plurality of modules each comprising a rotor disc is illustrated in FIGURES 4 to 6 of the accompanying drawings, and as shown, 10 indicates the switch housing in which a shaft 11 is rotatably mounted. Three rotor discs, each having cam-like peripheral surfaces, are mounted on the shaft 11. Only one rotor disc indicated by x is shown in FIGURE 6, but it will be understood that each of the rotor discs referred to will be adapted to control a pair of movable contacts such as a, b, each similar to that illustrated in FIGURES 1 to 3. The movable contacts a, b are in opposed relation, one on each opposite side of the rotor disc, the free end of the arm 1 of each movable contact is formed with a contact pip 2 on opposed faces and two opposed fixed contacts 9, 12 and 9a, 12a are provided, the latter contacts being provided on the ends of metal strips 13 having tailpieces extending through slots in the switch housing for connection to lead wires. The lugs S on the movable contacts also extend through slots in the switch housing for connection to lead wires, and the lug 5 and tag 5a of each contact serve to anchor the contacts to the switch housing.

When the parts are in the position indicated in FIG- URE 6, a portion of the peripheral cam surface x of the rotor disc x is in engagement with the resilient tongue 6 of the contact a to impart pressure to flex the body 1 of the contact into a position where the pip 2 engages the fixed contact 9. It will be noted that the tongue 6 has been slightly flexed towards the body 1-. Another cam surface at of the rotor disc x engages the tongue Got the contact b to maintain the contact in a vertical position wherein the pips 2 are in spaced relation between the fixed contacts 9a, 12a. I

It will be understoodthat in the particular embodiment illustrated in FIGURE 6, the cam surfaces 56 x on the rotor disc x will be so arranged that during a complete revolution of the disc, the movable contact a will be movable into a position wherein it engages the fixed contact 9, into a second position wherein it is spaced from the contacts 9' and 12, and into a third .position wherein it engages the fixed contact 12. The movable contact b will also be movable into a position whereinit engages the fixed contact 9a, into a second position wherein it'is spaced from the contacts 9a, 12 1, and into a third position wherein it engages the fixed contact 12a. The" arm lot the respective contact will'hinge about the bight'portion' 3 so as to be automatically moved into the second and third positions when permittedto do so by the contour of the respective cam surfaces. 7

As shown in FIGURE 6, when the contact a is engaging the fixed contact 9, the contact b is out of engager'nent with the fixed contacts 9a, 12a, but it will be understood that by suitably designing the cam on the rotor disc, the engagement of the movable contacts with the respective fixed contacts can-be'varied according to the requirements of the electrical circuits to be controlled by the switch; I V

The other rotor discs of the three module switch according to FIGURES 4 to 6 will also be provided with suitably shaped cam surfaces for controlling a pair of movable contacts relative to a pair of fixed contacts in a similar manner to that described above.

I The switch embodying the features of the present invention 'is particularly adapted for use'in caseswhere a variety of switching arrangements is required, for

example, for controlling the speed and heat of ,a fan heater wherein four switch positions are required, in the first of which the fan is controlled to operate at half speed and with half heat, in a second which provides full fan speed and half heat, a third position providing full.

tricalcircuits of a variety of appliances.

The switch can bebuilt up to include two or more 1 than three modules, each including a rotor disc for controlling the movable contacts.

While the-embodiment illustrated in FIGURES4 to 6 shows a pair or movable contacts controlled by each rotor disc, one or more of the rotor discs may be adapted to control only a single rnovable contact.

Iclaim: v I o A switch having a fixed contact and a movable contact, said movable contact formed of a single strip of conductive material and comprising a base portion, an arm connected: to the base portion by a bight portion and extending away from the base portion, the arm having a tongue cut from the material'thereof, the tongue being shorter in length than the arm and. having an arced portion formed therein andspaced from the arm for the major portion of the length of the tongue and which is flexed past the plane of theen'gaged portion of they arm and said movable contact actuated by a rotor having a lobe engageable with the arced portion of the tongue.

No reference cited.

ROBERT K. SCHAEFER, Primary Examiner- H. HOVHAUVSER, Assistant Examiner. 

